Refactor and merge CourseViewType and CourseTab.

TNL-2321

cms/templates/edit-tabs.html

@@ -4,7 +4,7 @@
 <%!
   from django.utils.translation import ugettext as _
   from django.core.urlresolvers import reverse
-  from openedx.core.djangoapps.course_views.course_views import StaticTab
+  from xmodule.tabs import StaticTab
   from django.template.defaultfilters import escapejs
 %>
 <%block name="title">${_("Pages")}</%block>